Chain-stitch sewing-machine



A. H. DE VOE.

CHAIN STITCH SEWING MACHINE.

APPLICATION FILED DEC-8,1917.

Patented Mar. 30, 1920.

2 SHEETSSHEET 1.

A TTORNEY A. H, DE VOEu CHAIN STKTCH SEWING MACHINE.

, APPLXCATION FILED DEC. 8, 19H. mmmw. Patented Min. 30,1920.

2 SHEETSSHEET 2.

ATTORNEY unirnn STATES PATENT OFFICE.

ALBERT H. DE VOE, OF WESTFIELD, NEW JERSEY. ASSIGNOR TO THESINGER MANU FACTURING COMPANY, A CORPORATION OF JERSEY.

CHAIN-STITCH SEWING-MACHINE.

Specification of Letters Patent.

Patented Mar. 30, 1920.

Application filed December 8, 1917. Serial No. 206,199.

To all whom it may concern Be it known that I, ALBERT H. DE Von, a citizen of the United States, residing at /Vestfield, in the countyof Union and State of New Jersey, have invented certain new and useful Improvements in Chain-Stitch Sewing-Machines, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention relates to sewing machines and especially to stitch-forming mechanisms for making chain-stitches as distinguished from lock-stitches. More specifically it relates to the type of chain-stitch machines in which a threaded needle cooperates with a non-thread carrying looper to form a single thread chain-stitch.

It aims to provide a new and useful ma chine of the chain-stitch type in which the needle-loop on the looper is properly presented to the needle for entrance thereby in order to insure the formation of stitches.

lit aims to insure the enchainment of a series of needle-thread loops without the use of spring-retainers which are liable to lose their elasticity or to become loose and cause the skipping of stitches.

It aims to make a more perfect chainstitch by lining up the successively enchained loops so that theylie in a straight line.

it also aims to improve the chain-stitch machine by simplifying itsconstruction.

In this invention the looper is moved enclwise across the direction of feed and it is shaped so as to hold the needle-loop back on the looper and to one side of the needlepath until the needle descends below the upper or supply or needle-limb when the lower or work-limb running to the previous stitch is shifted or cast across to the opposite side of the needle-path so as to distend the needle-loop for the entrance of the needle.

Other objects of the invention will appear as we proceed with the following description of the accompanying drawings in which Figure 1 is a side elevation of the machine showing the needle in its lowest position when the preceding stitch is being set. E2 is a sectional end elevation at the stitching point showing the needle about to leave the work after the looper has advanced past the needle. Fig. 3 is a view similar to Fig. 2 taken on a line through the needlehole in the throat plate and showing the looper in its retracting movement on the opposite side of the needlepath. Fig. 4t represents in perspective the needle and looper in the relative positions they occupy during the formation of the stitch, the needle-loop being shown in solid and dotted lines before and after respectively its limbs are turned or twisted relatively to throw them on opposite sides of the needlepath. Fig. 5isa front elevation of the needle and looper looking in the direction of feed with the needle shown in the position it occupies relative to the looper at the time the lower limb of the needle-loop is shifted across the needle-path andthe upper limb is held by the needle. Figs. 6 and 7 are front and rear views respectively of the looper-blade. Figs. 8, 9 and are cross sections on the radial lines a, b and 0, respectively, passing through the axis of the fulcrum-pin 22, Fig. 6, about which the looper vibrates. Fig. 11 is a plan view of the throatplate and feed-dog. Fig. 12 is a view of the stitch in its formation.

In the drawings a sewin machine is shown provided with the usual needle-bar 1 carrying the needle 2 at its lower end and reciprocated through any suitable mechanism such as the link 3, the needle-lever f and pitman 5 from an eccentric 6 on the mainshaft 7.

A presser-foot 8 of any suitable form, preferably of the tilting type shown, holds the work down on the throat-plate 9 provided with an elongated needle-hole 10 and feed-(log slots 11 through which latter a feed-dog 12 is given'four motions by mechanism well known in the art. The feed-dog 12 is cut out as shown at 13 to permit of operating the looper as closely as possible to the throat-plate and also has serrated or feed-sections front and back of the needle as shown clearly in Fig. 11 of the drawings.

The looper is moved endwise and preferably also sidewise by mechanism which will now be described. Secured upon the forward end of the rotary 1nain-shaft 7 is the split hub 14 of the tubular crank-element 15 having the axis of its cylinder bore inclined. to that of the shaft 7. To the bore side of the intersection of the axis of the tubular crank-element 15 with the axis of the main-shaft 7. From the inclined crankelement on the main-shaft the looper is thus given both endwise and bodily lateral movements in seizing and shedding the needleloop on opposite sides of the needle-path, which movements approximate simple harmonic motion there being substantially the same acceleration and retardation in the movement of the looper at the opposite ends of its stroke.

The shank 24 of the looper is secured by a screw 25 in a socket in the carriei 21. The loop taking portion 26 of the looper is thin and narrow like a blade and lies fiatwise in a plane substantially perpendicular to its fulcrum pin 22 and also transverse of the direction of feed. It may be of any desired shape and form provided it hasan enlargement or bulge 27 between its point or beak 28 and its heel 29 and provided also it has a deflecting or inclined surface 30 between the enlarged portion and the point. The form of the looper, shown in the front and rear views, Figs. 6 and 7 and in the sectional views, Figs. 8 to 10, has been found to give satisfactory results and represents one concrete form in which the invention has been successfully employed. It will be noticed that the front end of the looper is pyramidal in) form, that lmhind the enlarged portion the blade is slabbed off as shown in Fig. 10 so as to define a restraining or retarding means or portion indicated by the numeral 31. The radius of curvature of the upper surface or back of the blade is nearly the same as that of a circle whose radius is equal to the distance from the heel 29 of the looper to the axis of the fulcrumpin 22 but the point of the looper is preferably a less distance from the fulcrum-pin 22 than the heel. This explanation of the construction and shape of the looper together with the full illustration in the drawings, which disclose the specific shape of the looper better than language can tell, is believed to render this part of the invention clear to those skilled in the art.

A constant tensiondevice 32 of well known form is mounted onthe overhanging arm 33 being preferably supported in a bracket 34.

Thread-guides 35 and 36 are secured to the bracket 34 and their apertured ends are located at substantially diametrically opposite sides of the constant tension device 32 shown in Fig. 1 of the drawings. Between the thread-guide 35 and the constant tension device 32 is located the thread-engaging end of a spring-check 37 often called by those skilled in the art a slack-thread controller or an automatic take-up. This spring-check 37 is in the form of a wire bent about the supporting post'of the constant tension device in the manner fully shown in patent to Stedman No. 854,119, May 21, 1907, and therefore requiring no further description. No means are employed to control the thread other than this spring-check 37 in conjunction with the needle and looper. Thus the usual positivelv actuated take-up is dis pensed with, the needlebeing relied upon to set the previous stitch as it doubles the thread through the work on its descent.

In the operation of the machine as the 4 looper retracts or backs out of the needleloop the limbs of the needle-loop are dragged back in the direction that the looper is retracted owing to the increase in the thickness of the looper vertically which takes more thread from the previous needle puncture to encircle its front than its rear portion. The dragging of the needle-loop to one side of the needle-path is also caused by the fact that the front end of the looper is closer to its fulcrum or pivot 22 than its rear or heel end. When the needle-loop is in the position shown in solid lines, Fig. 4:, its thread has been put under tension partly by reason of the increased thickness of the looper toward its point, partly because the bodily sidewise movement of the looper is opposite to the direction of feed during the advance of the work, and partly because the needle-eye is at this time very close to the upper surface of the work, if not in it, and consequently making a sharp bend in the needle-thread above the work. This tensioning or tightening of the needle-thread about the looper together with the particular shape of the looper effectively drags or retains the needle-loop back on the looper and to one side of the needle-path until. the needle point descends below the upper or needle-limb. When the needle is moved an infinitely short distance from the position shown in solid lines Fig. f, the lower limb of the needle-loop is shifted 0r twisted or snapped along the inclined surface 30 by reason of the tension on the thread while the needle itself detains the upper or needle-limb of the needle-loop back on the looper. In this action the check-spring 37 draws up the slight amount of thread given up by the needle-loop as its lower limb is moved or shifted across the needle-path beneath the point of the needle and thus the check-spring 37 tends to prolong the shifting of said lower limb and to insure the positioning of the lower limb of the needle loop on opposite side oi. the needle-path from the upper limb. Thus the enchain ment of the needle-loops is eli ected largely by the specific shape of the looper and by the timing of the needles movement relative thereto so that it descends below one limb thereof and holds the same while the other limb is moving across the needle-path beneath the point of the descending needle. No retainer is required to shift the limbs of the loop on the looper out of vertical alinement and the needle and looper consti tute the sole instrumentalities for enchaining the needle-loops.

Having thus set forth the nature of the invention, what I claim herein is 1. In. a sewing machine having a throatplatc, a ,presser-foot, feeding mechanism, stitch-forming mechanism including a needle, a looper and means for advancing and retracting said looper transversely of the direction of feed, and said looper being shaped to shift the needle-loop when it is being shed from the looper in a direction opposite tothe movement of the looper when it is backing out of the needle-loop whereby the needle-loop may be presented to the neodle with its upper and lower limbs on opposite sides of the needle-path to insure the enchainment of the needle-loops.

2. In a sewing machine, in combination, worlz-advancing means, stitch-f0 rming mechanism including a needle and looper,means for moving said looper into and out of the needle-loop, said looper being shaped to shift the lower limb of the needle-loop on the looper toward the point of the looper when the needle has descended belowthe upper limb of the needle-loop.

3. In a sewing machine, in combination, work-feeding mechanism, stitch-forming mechanism including a needle and a looper, means for reciprocating said needle and moving said looper endwise in a direction transverse the feed, said looper having a blade with a pyramidal point and restraining means adjacent its upper edge to spread the needle-loop on the looper until the needle has descended into said needle-loop.

I. In a sewing machine, in combination, a throa -plate having a needle-hole elongated in the direction of feed, a reciprocatory needle, a looper having endwise movements across the line of feed and sidewise movements in the direction of feed for entering and shedding the needledoops, said looper being shaped to twist or turn the limbs of the needle-loop relatively and oppositely to the retractive movement of: the looper to spread them apart for the entrance of the needle.

5. In a sewing machine, in con ibination,

work-advancing means, stitch-forming mechanism including a needle and looper, means for advancing and retracting said looper into and out of the needle-loop, said looper being shaped to cast the limbs of the ncedlcloop on the looper out oi vertical, alinement and on opposite sides of the needle, a ten sion device located between the needle and the supply, and sel'l:'--acting thread-controlling Ineans located between the tension device and the needle.

6. In a chain-stitch sewing machine, a needle, means for reciprocating said needle, a looper, means for advancing and withdrawing said looper from the loop thrown out by the needle, means carried by the looper tor retarding one limb of the needle loop while it being shed from the looper, and means also carried by the looper for ejecting the other limb oil. the needle-loop whereby the needle-loop is flipped around the point of the needle during its descent.

7. In a chain-stitch sewing machine, a teed-dog having a plurality of separate and distinct toothed sections, a needle, a looper, means for advancing and retracting said. looper in a direction transverse the length of the teed-dog, said looper being shaped to throw the loop of needle-thread on the looper about the needle during its descent, and said :Feechclog having at least one toothed sec tion apertnred to permit the loopers ad vance into and retraction "from the needle loop in a path close to the work.

8. In a sewing machine having work-ad vancing means, in combination with stitchforming mechanism, a needle, a reciprocating looper shaped to shift aneedle-loop on the looper toward the point of the looper when the needle has descended below the upper limb of the needle-loop, and means tor moving said looper with the same acceleration and retardation at the opposite ends of its path of movement.

9. In a sewing machine having iccding mechanism, in combination with stitchliori'ning mechanism, a needle, :1 reciprocat ing looper, means on the looper :l'or retarding the shedding of one limb of the needleloop, means also on the looper for accelerat- 1.,

ing the shedding of the other limb of the needle-loop when the point of the needle has descended below the first-mentioned limb, and means for moving said looper with the same acceleration and retardation at the op posite ends of its path of movement.

10. In a sewing machine, a main-shaft, an inclined crank on said main-shalt, a reciprocating looper, means for actuating the looper from said inclined crank and imparting thereto an approximately simple harmonic motion, in combination with feeding mechanism and stitcl'l-forming mechanism.

including a needle, said looper having a pyranndal point in proxnnity to a restrain.-

ing means for flipping a loop of thread about the point of a descending needle during successive stitch-forming cycles of operation.

11.7111 ztsewi'ng machine, in combination, work-advancing means, stitch-forming mechanism including a needle and looper, means for moving said looper into and out of the needle-100p, means upon and adjacent the 10 point of the loopei' for retarding the shedposite side of the needle-1mm as the needle descends. V

In testimony whereof, I. have signed my name to this specification.

ALBERT H. DE V019. 

